Blockages or obstructions, such as stones or calculi can develop in certain parts of the body, including the kidneys, pancreas, esophagus, and gallbladder. Minimally invasive surgical procedures, typically involving percutaneous insertion of a retrieval device through an endoscope or laparoscope, may be used to break up and remove such blockages. For example, currently available medical retrieval devices provide physicians with the ability to retrieve stones that are in easily accessible areas of the urinary tract.
One type of retrieval device, known as a “basket” retrieval device, typically is formed of a wire assembly that surrounds a captured stone or calculi during retrieval. Many known basket-type devices collapse into the distal end of a catheter during insertion, and are extended from the end of the catheter when deployed. Basket-type retrieval devices typically require a physician to advance the device past the stone mass, deploy the retrieval device, and then pull it back toward the stone to capture the stone.
Difficulties can arise when using such a basket device when, for example, a stone becomes stuck or wedged during removal. In such a situation, damage to surrounding tissue or tissue lining may result if the physician forces the basket and stone through an area in which the stone has become stuck or wedged. To avoid such damage, it may be necessary to release the stone and break it into smaller fragments. Unfortunately, typical basket retrieval devices do not allow the physician to release easily the stone and continue breaking it up before removal is again attempted.
To address these difficulties, stone removal can be accomplished using a grasper, instead of a basket device. Typically, a grasper is a device having three or four prongs that are manipulated to capture a stone from the front side of the stone, by grasping it. When a stone becomes stuck or wedged during removal, such graspers are able to release the stone. Unfortunately, graspers typically do not hold on to stones as well as baskets. It may be difficult to capture a stone using a grasper, and once captured, it is easy for the stone to be released inadvertently.
Over the course of a procedure, a physician may need to use both graspers and basket-type devices to manipulate a stone, break up the stone, and remove fragments of the stone. Using current graspers and baskets, a physician may need to switch devices during the procedure. Switching devices typically requires withdrawal of one device and insertion of another.